First, let's be clear on the accuracy standard that underpins the whole… — Page 227, Lesson 228

I want to walk you through the rules for submitting a flight plan — when you do it, how you do it, and what happens if you're delayed. This is a core procedural area you'll use every time you fly under instrument or controlled conditions. First, let's be clear on the accuracy standard that underpins the whole flight plan. The navigation accuracy expected is +/- 4 nautical miles on a 95% containment basis. That means when you file a route, the air traffic services unit expects your aircraft to stay within 4 nautical miles left or right of the planned track 95% of the time. It's not a guarantee you'll be perfect every second — it's a statistical containment. If your navigation system can't hold that, the flight plan may not be acceptable for the airspace you're entering. Now, the submission rules. There are two main timeframes: prior to departure and during flight. Prior to departure — this is the normal case. Except when you've made other arrangements for something called a repetitive flight plan (that's a standing plan filed for a regular schedule, like a daily airline service), a flight plan submitted before departure should be submitted in person or by telephone to the air traffic services reporting office at the departure aerodrome. That's the physical office at the airport where you hand in or call in your plan. If no such reporting office exists at your departure aerodrome — say you're at a small uncontrolled field — then you submit the flight plan by telephone or typewriter. If those means aren't available either, you submit by radio to the unit that serves or is designated to serve that departure aerodrome. So the chain is: in person or phone to the reporting office first; if no reporting office, phone or typewriter to the serving unit; if those aren't available, radio to that unit. There's a critical timing rule for delays. If you've submitted a flight plan and your departure is delayed 30 minutes in excess of the estimated off-block time for a controlled flight, or one hour for an uncontrolled flight, you must take action. You should either amend the existing flight plan, or submit a new flight plan and cancel the old one — whichever is applicable. So for a controlled flight, the clock starts ticking from your estimated off-block time; if you're still on the ground 30 minutes past that, you can't just sit on the old plan. For an uncontrolled flight, you get a full hour before you have to update it. During flight — if you need to submit a flight plan while already airborne, the normal method is to transmit it to the aeronautical telecommunication station that serves the air traffic services unit in charge of the flight information region, control area, advisory area, or advisory route in or on which you wish to fly. That's a mouthful, so let me break it down. You send your flight plan to the radio station that handles communications for the ATC unit responsible for the airspace you want to enter. If that's not practicable — maybe you can't reach that station directly — you transmit it to another aeronautical telecommunication station, and they retransmit it as needed to the appropriate air traffic services unit. So the system is designed to get your plan to the right controller even if you can't talk to them directly. That's the submission procedure — before departure, with the delay rules, and during flight.